Hybrid component

ABSTRACT

A hybrid torsion beam axle assembly is provided, which includes a steel torsion beam. An end cap is fastened to an end portion of the steel torsion beam, and a cast trailing arm is cast about the end portion of the steel torsion beam including the end cap. In this way, the cast trailing arm is positively and rigidly secured to the steel torsion beam.

This application is a continuation-in-part of U.S. patent applicationSer. No. 10/576,377, filed on Apr. 25, 2007, now U.S. Pat. No. 7,837,230which is a National Phase entry of PCT Application No. PCT/US04/034504filed on Oct. 20, 2004 which claims the benefit of U.S. provisionalapplication No. 60/512,827, filed on Oct. 20, 2003 and 60/612,800, filedon Sep. 27, 2004. This application is also a continuation-in-part ofU.S. patent application Ser. No. 12/871,329, filed on Aug. 30, 2010,which is a continuation-in-part of U.S. patent application Ser. No.11/913,736, filed on Dec. 14, 2007, now U.S. Pat. No. 7,806,162 which isa National Phase entry of PCT Application No. PCT/CA06/000820 filed onMay 19, 2006, which claims the benefit of U.S. provisional applicationNo. 60/682,329, filed on May 19, 2005. The entire disclosures of each ofthe above-noted applications are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to an automotive component, andmore specifically, to a hybrid component for use in an automobilesuspension, chassis, body or power train component such as but notlimited to torsion beam, control arm, engine mount, sub-frame ortransmission pump that is at least partially formed by using acast-in-place operation.

BACKGROUND OF THE INVENTION

Typically, a conventional arm member for use as an automobile suspensionarm is comprised of a machined aluminum casting, iron casting or formedsteel structure and a pair of elastomeric bushings pressed in each endof the member. In the case of a tubular formed steel structure, variousfusion welding (MIG welding, TIG welding or laser welding), or frictionagitation welding, have been developed to connect the coupling membersto the tubular member at a joined portion. Known casting methods includethose disclosed in U.S. Pat. Nos. 5,332,026, 5,429,175, 5,660,223,6,467,528, and 6,745,819, the entire contents being incorporated hereinby reference.

However, a conventional suspension arm member, for example, in which themain body and the coupling member are joined by using a welding method,such as fusion welding (MIG welding, TIG welding, laser welding, or thelike) or a solid-phase welding method (friction agitation welding), maycause cracks at or proximate to the joined portion when a tensile loadis imparted thereto resulting in separation of the joined members andreduced functionality. Further, to achieve a reduction in mass of theconnecting member, the connecting member may be tubular in shape.Conventionally, the connecting member and coupling members are ofsimilar chemical composition or metallurgically compatible to permit useof a fusion welding process used to connect the members to achieve thestrength and corrosion resistance requirements of the product. Thus,there is a need to provide a component for an automobile suspension,structure, body or power train application that is light in weight andvoid of potential quality issues related to strength, cracks andcorrosion.

Conventional aluminium high pressure die casting utilizes a hydrauliccylinder to advance a shot tip, displacing molten aluminium from theshot sleeve into the die cavity, overcoming the resistance to flowthrough the restricted gate area. When the die cavity is filled withmolten aluminium, the pressure applied to the hydraulic shot cylinder istransferred to the molten aluminium based upon the ratio of the shotcylinder and shot tip cross-sectional area. If the die cavity containingone end of a submerged member fills and becomes pressurized before thedie cavity or region of the die containing the opposing end of thesubmerged member, a resultant force is imposed on the end of thesubmerged member. To avoid movement of the submerged member, a mechanismmust be employed, such as a clamp or a friction or form fitting die, toresist the force. As the cross-sectional area of the member increases,the forces become very high and difficult to manage with suchmechanisms. Subsequent to filling of the die cavity, the pressureapplied to the hydraulic cylinder advancing the shot tip is typicallyincreased (i.e., intensified) by, for example, a factor of two times toreduce the volume of entrapped air and increase the rate of heattransfer. Also, once the in-gates have frozen-off through solidifying,which usually occurs prior to the solidifying of the entire die cavity,even the increased pressure fails to reach the material within thecavities being molded.

U.S. Pat. No. 3,664,410 to Groteke and U.S. Pat. No. 4,779,666 toRuhlandt et al., disclose each a die casting process and apparatus.

SUMMARY OF THE INVENTION

The inventors of the present invention have recognized these and otherproblems associated with conventional components. To alleviate suchproblems, an aspect of the invention relates to a method of forming ahybrid component that includes deforming an open end of a tubular memberto seal the open end, and casting molten material about the deformedopen end to form a coupling member.

The deforming step may further comprise crushing or pinching the openend to seal the open end. The deforming step may further comprisefolding the sealed open end on itself to form a J-hook attachmentfeature. Also, the deforming step may further comprise folding the openend.

Another aspect of the invention relates to a method of forming a hybridcomponent that includes inserting a cap member into or around an openend of a tubular member, and casting molten material about the tubularmember and cap member to form a coupling member.

The method may further comprise the steps of piercing the tubular memberand an outer wall of the cap member, and inserting a pin into thepierced tubular member and cap member.

Another aspect of the invention relates to a hybrid component thatincludes a tubular member having a deformed open end, and a couplingmember formed on the deformed open end of the tubular member bycasting-in-place molten material about the deformed open end, therebypositively securing the coupling member to the tubular member.

The component may further comprise a plug partially received in the openend, and a pin received through holes formed in the tubular member andthe plug.

Another aspect of the invention relates to a method that comprises thesteps of rotary swedging the open end of a tubular member to seal theopen end, and casting molten material about the deformed end to form acoupling member.

Another aspect of the invention relates to a method that comprises thesteps of applying a nickel-based coating material onto the surface ofthe closed end of a tubular member to form a coupling member.

Another aspect of the invention relates to a hybrid component forlightweight, structural uses. The hybrid component includes a steelmember and a cast coupling member cast on a portion of the steel memberby casting-in-place aluminum about the portion of the steel member,thereby positively and rigidly securing the coupling member to the steelmember.

The steel member may be a tubular member. The portion of the steelmember on which the coupling member is cast may be an end portion of thetubular member. The end portion may include bent sections extendingoutwardly away from the steel member. The end portion may include asection having a non-circular cross-section. The portion of the steelmember on which the coupling member is cast may be a mid portion of thetubular member. The mid portion may include a section having anon-circular cross-section.

Another aspect of the invention relates to an engine cradle for a motorvehicle. The engine cradle includes a frame assembly having a pair ofspaced rails secured by spaced cross members. At least one of the spacedrails and the spaced cross members include a hybrid component includinga steel member formed of a high strength steel and a cast couplingmember cast on a portion of the steel member by casting-in-placealuminum about the portion of the steel member, thereby positively andrigidly securing the coupling member to the steel member.

Another aspect of the invention relates to a control arm for a motorvehicle. The control arm includes a hybrid component including a steelmember formed of a high strength steel and curved in a longitudinaldirection and cast coupling members cast on the steel member. Each ofthe coupling members are cast on a portion of the steel member bycasting-in-place aluminum about the portion of the steel member, therebypositively and rigidly securing the coupling member to the steel member.

Another aspect of the invention relates to an instrument panel supportstructure for a motor vehicle. The instrument panel support structureincludes a hybrid component in the form of a cross beam and a mountpositioned on each end of the hybrid component. The hybrid componentincludes a steel member formed of a high strength steel and a castcoupling member cast on the steel member. The coupling member is cast ona portion of the steel member by casting-in-place aluminum about theportion of the steel member, thereby positively and rigidly securing thecoupling member to the steel member. The cast coupling member includes aplurality of spaced brackets.

Another aspect of the invention relates to a bumper assembly for a motorvehicle. The bumper assembly includes a hybrid component including asteel member formed of a high strength steel and cast coupling memberscast on the steel member. Each of the coupling members are cast on aportion of the steel member by casting-in-place aluminum about theportion of the steel member, thereby positively and rigidly securing thecoupling members to the steel member. The steel member forms alongitudinally extending steel bumper member constructed to protect thevehicle from impact, and the coupling members form first and secondaluminum members attached to the steel bumper member. The steel bumpermember extends between the first and second aluminum members and thefirst and second aluminum members are positioned between the steelbumper member and the space frame of the vehicle.

Another aspect of the invention relates to a method of forming a hybridcomponent for lightweight, structural uses. The method includes forminga steel member formed of a high strength steel into a predeterminedconfiguration and casting a coupling member on a portion of the steelmember by casting-in-place aluminum about the portion of the steelmember, thereby positively and rigidly securing the coupling member tothe steel member.

The forming the steel member may include forming the steel member tohave a yield strength of at least about 1300 MPa, and the casting thecast coupling may include forming the aluminum to have a yield strengthof at least about 180 MPa. The forming the steel member may includeforming the steel member as a tubular member. The method may furthercomprise heat treating the hybrid component to an elevated temperature.The heat treating the hybrid component to an elevated temperature mayinclude heat treating the hybrid component to approximately 400° F.

Another aspect of the invention relates to a bumper assembly for avehicle. The bumper assembly includes a longitudinally extending steelbumper member constructed to protect the vehicle from impact, and firstand second aluminum members attached to the steel bumper member. Thesteel bumper member extends between the first and second aluminummembers and the first and second aluminum members are positioned betweenthe steel bumper member and the space frame of the vehicle.

The first and second aluminum members may be mounting brackets having amounting plate configured to mount the bumper member to the space frame.Also, the first and second aluminum members may be plates. Further, thefirst and second aluminum members may be crush cans configured to absorba collision force and deform in predetermined manner.

Another aspect of the invention relates to a method of manufacturing abumper assembly for a vehicle. The method includes forming alongitudinally extending steel bumper member constructed for protectingthe vehicle from impact, forming first and second aluminum members,attaching the first and second aluminum members to the steel bumpermember such that the steel bumper member extends between the first andsecond aluminum members, and the first and second aluminum members beingpositioned between the steel bumper member and the space frame of saidvehicle.

The forming of the bumper member may include forming the bumper memberby one of roll-forming, stamping, and hot stamping. Also, the forming ofthe first and second aluminum members may include forming the first andsecond aluminum members by extrusion. Further, the forming of the firstand second aluminum members may include forming the first and secondaluminum member with an aluminum portion and a steel portion.Additionally, the method may further comprise attaching a nonmetallicimpact-absorption device to the steel member.

Another aspect of the invention relates to a bumper assembly for avehicle. The bumper assembly includes longitudinally extending tubularmembers constructed to protect the vehicle from impact, and first andsecond mounting members attached to the tubular members to mount thetubular members to the space frame of the vehicle. The tubular membersextend between the first and second mounting members and the first andsecond mounting members are positioned between the tubular members andthe space frame of the vehicle.

The tubular members may include two substantially parallel tubularmembers. The mounting members may be aluminum and each of the mountingmembers fully encapsulates an end of each of the two tubular members.The bumper assembly may further comprise a middle member attached to andextending between the tubular members. The middle member may extendsubstantially along the entire length of the tubular members. The bumperassembly may further comprise a nonmetallic impact-absorption deviceattached to the tubular members. Also, each of the tubular members maybe hollow.

Another aspect of the invention relates to a method of manufacturing abumper assembly for a vehicle. The method includes forming alongitudinally extending bumper member constructed to protect thevehicle from impact, casting a first mounting member on a first end ofthe steel bumper member, and casting a second mounting member on asecond end of the steel bumper member.

The forming a longitudinally extending bumper member may include forminga steel bumper member. The casting of the first and second mountingmembers may include casting aluminum mounting members. The method mayfurther comprise attaching the first and second mounting members to thespace frame of the vehicle. The method may further comprise attaching anonmetallic impact-absorption device to the bumper member. The formingof the bumper member may include forming the bumper member byhydroforming. Also, the forming the bumper member may include formingthe bumper member by roll-forming.

Another aspect of the invention relates to a method of manufacturing abumper assembly for a vehicle. The method includes forming a firstlongitudinally extending tubular bumper member constructed to protectthe vehicle from impact, casting a first mounting member on a first endof the first tubular bumper member, and casting a second mounting memberon a second end of the first tubular bumper member.

The method may further comprise forming a second longitudinallyextending tubular bumper member constructed to protect the vehicle fromimpact, and wherein the casting of the first and second mounting membersmay include casting the first mounting member on a first end of thesecond tubular bumper member and casting the second mounting member on asecond end of the second tubular bumper member. The forming alongitudinally extending tubular bumper member may include forming asteel tubular bumper member. The casting of the first and secondmounting members may include casting aluminum mounting members. Themethod may further comprise attaching the first and second mountingmembers to the space frame of the vehicle. The method may furthercomprise attaching a nonmetallic impact-absorption device to the bumpermember. The forming the first tubular bumper member may include formingthe tubular bumper member by hydroforming. The forming of the firsttubular bumper member may include forming the tubular bumper member byroll-forming. Also, the forming of the first tubular bumper member mayinclude forming a hollow tubular bumper member.

Another aspect of the invention relates to a method of forming compositemetal castings, in which a first end of a structural member ispositioned in a first mold cavity and a second end of the structuralmember is positioned in a second mold cavity. The first and second moldcavities are fluidly coupled to a reservoir of molten metal. A mainpressure is applied to the molten metal in the reservoir to force themolten metal into the first mold cavity and the second mold cavity. Afirst auxiliary pressure is applied to the molten metal in the firstmold cavity and a second auxiliary pressure is applied to the moltenmetal in the second mold cavity to densify the casting formed in thefirst mold cavity and in the second mold cavity.

Another aspect of the invention relates to a method of forming metalcastings, comprising: positioning a first end of a structural member ina first mold cavity, the first mold being fluidly coupled to a reservoirof molten metal; applying a main pressure to the molten metal in thereservoir at an initial, mold-filling pressure to force the molten metalinto the first mold cavity; applying a first auxiliary pressure to themolten metal in the first mold cavity; and maintaining the main pressureat or less than the initial, mold-filling pressure after the first moldcavity has been filled.

Another aspect of the invention is a method of forming metal castings,comprising: positioning a first end of a structural member in a firstmold cavity, the first mold cavity being fluidly coupled to a reservoirof molten metal; applying a main pressure to the molten metal in thereservoir to force the molten metal into the first mold cavity;detecting whether the first mold cavity is sufficiently filled withmolten metal by monitoring a moveable element; and applying a firstauxiliary pressure to the first mold cavity after detecting that thefirst mold cavity is sufficiently filled.

Another aspect of the invention relates to a twist axle assembly for amotor vehicle. The twist axle assembly includes a hybrid componentincluding a steel member formed of a high strength steel and curved in alongitudinal direction and cast coupling members cast on the steelmember. Each of the coupling members are cast on a portion of the steelmember by casting-in-place aluminum about the portion of the steelmember, thereby positively and rigidly securing the coupling member tothe steel member.

The steel member may have a yield strength of at least about 1300 MPa,and each of the cast couplings may have a yield strength of at leastabout 180 MPa. The steel member may be a tubular member.

Another aspect of the invention relates to a hybrid component for anautomobile, comprising: a steel member; and a cast coupling member caston a portion of said steel member by casting-in-place a casting materialabout said portion of said steel member, thereby positively and rigidlysecuring said coupling member to said steel member.

Another aspect of the invention relates to a composite casting,comprising: a steel member; an end cap fixedly secured to an end portionof the steel member and having an outwardly projecting flange, theflange having one of a circular and a non-circular configuration; and acast coupling member cast about the end portion of the steel memberincluding the end cap, thereby positively and rigidly locking andsecuring said cast coupling member to said steel member.

Another aspect of the invention relates to a hybrid torsion beam axleassembly, comprising: a steel torsion beam; an end cap fixedly securedto an end portion of the steel torsion beam; and a cast trailing armcast about the end portion of the steel torsion beam including the endcap, thereby positively and rigidly securing the cast trailing arm tothe steel torsion beam.

Another aspect of the invention relates to a method of forming a hybridcomponent, comprising: forming a steel member into a predeterminedconfiguration; providing an anchor structure on a portion of the steelmember; and casting a coupling member about the anchor structure bycasting-in-place a casting material about the anchor structure, therebypositively and rigidly securing the coupling member to the steel member.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention will now be described inconjunction with the following drawings, wherein similar referencenumerals denote similar elements throughout the several views, in which:

FIG. 1 is a perspective view of a hybrid component according to anembodiment of the invention;

FIG. 2 is a partial cutaway view of a hybrid component according to anembodiment of the invention in which an end portion is crushed andfolded over on itself to form a J-hook attachment feature;

FIG. 3 is an exploded view of the hybrid component of FIG. 2;

FIG. 4 is a partial cutaway view of a hybrid component according to anembodiment of the invention in which an end portion is crushed to form aY-hook attachment member;

FIG. 5 is an exploded view of a hybrid component according to anotherembodiment of the invention;

FIG. 6 is a partial cutaway view of the hybrid component of FIG. 5 inwhich a pin is inserted into holes in the tubular member and the capmember;

FIG. 7 is a partial cutaway view of the hybrid component of FIG. 5 inwhich the pin and holes in the tubular member and the cap member areomitted;

FIG. 8 is a perspective view of an engine mount incorporating hybridcomponents according the principles of the invention;

FIG. 9 is a side view of a hybrid component according to anotherembodiment of the invention;

FIG. 10 is a cross-sectional view through line 10-10 of FIG. 9;

FIG. 11 is a cross-sectional view through line 11-11 of FIG. 9;

FIG. 12 is a top view of the hybrid component shown in FIG. 9;

FIG. 13 is a cross-sectional view through line 13-13 of FIG. 12;

FIG. 14 is a side view of a hybrid component according to anotherembodiment of the invention;

FIG. 15 is a cross-sectional view through line 15-15 of FIG. 14;

FIG. 16 is a cross-sectional view through line 16-16 of FIG. 14;

FIG. 17 is a cross-sectional view through line 17-17 of FIG. 14;

FIG. 18 is a cross-sectional view through line 18-18 of FIG. 14;

FIG. 19 is a cross-sectional view through line 19-19 of FIG. 14;

FIG. 20 is a side view of a hybrid component according to anotherembodiment of the invention;

FIG. 21 is a cross-sectional view through line 21-21 of FIG. 20;

FIG. 22 is a cross-sectional view through line 22-22 of FIG. 20;

FIG. 23 is a cross-sectional view through line 23-23 of FIG. 20;

FIG. 24 is a cross-sectional view through line 24-24 of FIG. 20;

FIG. 25 is a perspective view of an automotive rear cradle incorporatinghybrid components according an embodiment of the invention;

FIG. 26 is a perspective view of an automotive rear cradle incorporatinghybrid components according an embodiment of the invention;

FIG. 27 is a perspective view of a hybrid control arm constructedaccording to an embodiment of the invention;

FIG. 28 is a perspective view of a hybrid control arm constructedaccording to an embodiment of the invention;

FIG. 29 is a perspective view of an instrument panel support systemconstructed according to an embodiment of the invention;

FIG. 30 is a perspective view of tubular cross-beam of the supportsystem shown in FIG. 29;

FIG. 31 is a perspective view of a main steering column/instrumentcluster bracket of the support system shown in FIG. 29;

FIG. 32 is a left-hand mounting bracket of the support system shown inFIG. 29;

FIG. 33 is a right-hand mounting bracket of the support system shown inFIG. 29;

FIG. 34 is an exploded view illustrating a bumper assembly constructedin accordance with an embodiment of the invention;

FIG. 35 is a front perspective view illustrating a middle member of thebumper assembly shown in FIG. 34 attached to tubular members of thebumper assembly shown in FIG. 34;

FIG. 36 is an enlarged front perspective view illustrating a mountingmember of the bumper assembly shown in FIG. 34 attached to tubularmembers of the bumper assembly shown in FIG. 34;

FIG. 37 is a rear perspective view illustrating another embodiment of abumper assembly;

FIG. 38 is an enlarged front perspective view illustrating a mountingmember of the bumper assembly shown in FIG. 37 attached to a middlemember of the bumper assembly shown in FIG. 37;

FIG. 39 is an enlarged rear perspective view illustrating a mountingmember of the bumper assembly shown in FIG. 37 attached to a middlemember of the bumper assembly shown in FIG. 37;

FIG. 40 is a front perspective view illustrating another embodiment of abumper assembly;

FIG. 41 is an enlarged front perspective view illustrating a mountingmember of the bumper assembly shown in FIG. 40 attached to a middlemember of the bumper assembly shown in FIG. 40;

FIG. 42 is an enlarged rear perspective view illustrating a mountingmember of the bumper assembly shown in FIG. 40 attached to a middlemember of the bumper assembly shown in FIG. 40;

FIG. 43 is an exploded view illustrating another embodiment of a bumperassembly;

FIG. 44 is an enlarged perspective view illustrating a mounting memberof the bumper assembly shown in FIG. 43 attached to a connecting memberof the bumper assembly shown in FIG. 43;

FIG. 45 illustrates a schematic of one illustrated embodiment of thepresent invention;

FIG. 46 illustrates the embodiment of FIG. 45 with the molten metalpartially filling the molds;

FIG. 47 illustrates the embodiment of FIG. 45 with the molten metalcompletely filling the molds;

FIG. 48 illustrates the embodiment of FIG. 45 with the auxiliarypressure being applied to the molten metal in the molds;

FIG. 49 illustrates the embodiment of FIG. 45 with the molten metalpartially solidified, in the reservoir;

FIG. 50 illustrates a method in accordance with one aspect of theinvention;

FIG. 51 illustrates a method in accordance with another aspect of theinvention;

FIG. 52 illustrates a method in accordance with yet another aspect ofthe invention;

FIG. 53 illustrates a schematic of another embodiment of the presentinvention wherein four molds are in operation simultaneously to form twovehicle cradles;

FIGS. 54-60 illustrate various examples of tube end closing andmechanical interlock for use with the present invention;

FIG. 61 shows a flat end cap abutting with an end portion of a steelmember;

FIG. 62 shows the end cap of FIG. 61 positively and rigidly locking andsecuring a cast coupling member to the steel member;

FIGS. 63 a-e show exemplary embodiments of end cap designs;

FIG. 64 shows a hybrid torsion beam axle assembly according to anembodiment of the instant invention;

FIG. 65 shows an enlarged perspective view of one end of the hybridtorsion beam axle assembly of FIG. 64;

FIG. 66 is partial cut-away section of the one end of the hybrid torsionbeam axle assembly shown in FIG. 65; and,

FIG. 67 shows a second perspective view of the flange structure of theend cap that is fastened to one end of the torsion beam of FIG. 64.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

The subject application discloses a method employing a casting processto fabricate structural components, e.g., automotive structuralcomponents, comprised of a preformed steel insert and cast aluminum. Themethod involves placing a preformed steel member, e.g., a tube, into aconventional steel casting die, casting aluminum around specificsections of the steel member, and creating a component comprised ofdissimilar materials (e.g., steel and aluminum). Examples of suitablealuminum casting processes include high pressure aluminum die casting,low pressure permanent mold, lost foam casting, squeeze cast, vacuum diecast, semi-solid casting, or the like. The hybrid material(aluminum/steel) structural component may be subsequently heat treated(artificially aged at an elevated temperature of approximately 400° F.)to a T5 heat treatment specification to improve the mechanicalproperties of the cast aluminum. Subsequent to the heat treatmentprocess, the component may be machined and assembled using conventionalprocessing and methods. (It should be understood that the reference to“steel” and “aluminum” are intended to encompass materials that includesteel and aluminum, respectively, and to include various alloys of steeland aluminum being made of various chemical elements).

When the aluminum castings are manufactured using the semi-solid castingprocess, a solution heat treatment cycle is not required to achieve anacceptable yield strength, typically greater than 180 MPa. Semi-solidcastings have yield strength greater than 180 MPa with merely anartificial aging (T5) heat treatment cycle, which involves exposing thealuminum casting to a temperature of approximately 400° F. (220° C.).Thus, the components of the subject application as described in theillustrated embodiments discussed below have the ability to befabricated from a cast aluminum/steel hybrid component having a yieldstrength of a cast aluminum greater than about 180 MPa and a steel yieldstrength greater than about 1,300 MPa. This can be accomplished if thecast aluminum/steel hybrid component is not exposed to the aluminumsolution heat treatment temperature (typically 1000° F.). As notedabove, the semi-solid aluminum casting process provides the ability toobtain a minimum yield strength of 180 MPa by subjecting the hybridcomponent to a T5 artificial age heat treatment (typically 400° F.),thus avoiding degradation of the steel material properties which resultsfrom “overtempering” during the aluminum solution heat treatmentprocessing. Thus, the subject application discloses apparatus andmethods that provide components that are relatively strong yetrelatively lightweight.

Referring now to FIG. 1, a hybrid component 10 is shown according to anembodiment of the invention. In the illustrated embodiment, the hybridcomponent 10 can be used as a suspension arm 10 in a vehicle. The hybridcomponent 10 comprises a tubular member 12 made of a metal material,such as steel, aluminum, or the like. The tubular member 12 may be heattreated. The tubular member 12 can be formed to any desired shaped byusing any conventional process. For example, the tubular member 12 canbe formed using a hydroforming process, or the like, thereby forming ahydrocast hybrid component. The hybrid component 10 also includes a pairof substantially identical attachment or coupling members 14 made ofaluminum die casting and connected to longitudinal opposite end portions16 of the tubular member 12. As used herein, the term “aluminum” denotesaluminum and its alloys. A bushing 18 may be forcibly fitted into andsecured by each coupling member 14, and a sleeve 20 may be fitted withinthe bushing 18, as shown in FIG. 2.

Referring now to FIGS. 2 and 3, one aspect of the invention is themethod in which the coupling member 14 is secured to the tubular member12. Specifically, the invention contemplates a method of securing thecoupling member 14 to the tubular member 12 using a cast-in-placetechnique, rather than using a conventional welding technique. The casttechnology used to form the coupling member 14 can be, for example, highpressure aluminum die casting, low pressure permanent mold, lost foamcasting, squeeze cast, vacuum die cast, semi-solid casting, or the like.As shown in FIGS. 2 and 3, one or both end portions 16 of the tubularmember 12 is deformed by crushing or pinching such that the end portion16 of the tubular member 12 is sealed to prevent the ingress or influxof the molten casting material into the tubular member 12 during thecast-in-place technique, and to eliminate any gaps between the tubularmember 12 and each end portion 16. Also, the crush forming operationalso distorts the shape of tubular member 12 and, thus, increases thetorsional strength of the hybrid assembly. In addition, the end portion16 is folded upon itself to form a J-hook attachment feature thatprovides a mechanical lock or joint between the coupling member 14 andthe tubular member 12. In this manner, the coupling member 14 ispositively secured to the tubular member 12. Also, the J-hook increasesthe tensile strength of the hybrid assembly. In addition, to increasethe strength of the joint between the deformed tubular member 12 and thecoupling member 14, single or multiple openings may be created in thedeformed tubular member 12 using conventional drill, pierce or cuttingprocesses which are filled with cast material during the cast-in placetechnique.

It should be understood that the form of the crushed ends of tubularmember 12 illustrated in the figures provides examples of crushed forms,but that the form and shape of the crushed ends can be tailored basedupon the functional use of the part, such as the arm 10 and its functionrequirements.

Referring now to FIG. 4, another embodiment of the invention is shown inwhich the cast-in-place coupling member 14 is secured to the tubularmember 12. Specifically, the tubular member 12 is deformed by crushingthe end portion 16 of the tubular member 12 to completely seal andprevent the ingress or influx of the molten casting material into thetubular member 12 during the cast-in-place technique. In addition, theend portion 16 forms a Y-hook attachment feature that provides amechanical lock or joint between the coupling member 14 and the tubularmember 12. In this manner, the coupling member 14 is positively securedto the tubular member 12 and attachment between the end portion and thetubular member can be accomplished without crevices or openings betweenthe two elements that could cause galvanic corrosion.

Referring now to FIGS. 5-7, another embodiment of the invention is shownin which the cast-in-place coupling member 14 is secured to the tubularmember 12. As best shown in FIG. 5, the end portion 16 of the tubularmember 12 is pierced to form a hole 22. In addition, the end portion 16is slightly flared outwardly for receiving a cup-shaped cap member orplug 24 having a hole 26. The hole 22 of the tubular member 12substantially aligns with the hole 22 in the plug 24 when the plug 24 isinserted into the end portion 16 of the tubular member 12. The plug 24can be held in place by a friction force (interference fit), by apiercing or drilling operation, or mechanically via a hollow sleeve orpin. In the illustrated embodiment, at least a hollow pin is employed.Once the holes 22, 26 are aligned with each other, a pin 28 can beinserted through both holes 22, 26 to hold the plug 24 in place. As bestshown in FIG. 6, the molten aluminum is allowed to flow into the plug 24and the pin 28 to positively secure the coupling member 14 to thetubular member 12. It will be appreciated that the holes 22, 26 and thepin 28 are optional and may be omitted, as shown in FIG. 7. The plug 24has a melting point greater than that of the molten cast metal andsufficient strength to avoid mechanical failure associated with thepressure casting process. Also, the plug may extend into the end portion16 as described above, or the plug may be structured such that itextends around the outside diameter of the end portion 16.

Referring now to FIGS. 9-13, another embodiment of the invention isshown in which the cast-in-place coupling member 14 is secured to thetubular member 12. In this embodiment, the open end portion 16 of thetubular member 12 is closed and sealed by a rotary swedging process, andthen molten material is cast about the deformed end to form the couplingmember 14. The rotary swedging process, hammers the periphery of thetubular member 12 to deform and close the end of the tubular member 12without the use of a cap member. Further, the rotary swedging processforms a non-uniform shape or undercut 32 in the tubular member 12. Thenon-uniform shape 32 provides a mechanical lock or joint between thecoupling member 14 and the tubular member 12 to prevent the couplingmember 14 from slipping off the tubular member 12. Also, the non-uniformshape 32 increases tensile strength of the joint.

In the illustrated embodiment, the rotary swedging process also forms anon-circular shape, e.g., hexagon, octagon, etc, on the tubular member12 including the end portions 16 as shown in FIG. 10. This provides aradial lock between the coupling member 14 and the tubular member 12 andincreases the torsional strength of the joint.

Also, the rotary swedging process may be used around a loose piece plugto secure the plug to the open end of the tubular member. This resultsin closure of the open end portion of the tubular member at a low costand weight. Further, this arrangement provides an opportunity to closelarge diameter tubular sections.

In addition, to increase the strength of the joint between the deformedor capped tubular member and the coupling member, single or multipleopenings may be created in the tubular member using conventional drill,pierce or cutting processes which are filled with cast material duringthe cast-in place technique.

In addition, to increase the strength of the joint between the deformedor capped tubular member and the coupling member, a nickel-based alloymay be applied to the surface of the tubular member using conventionalcoating processes such as laser deposition (DMD), Plasma Transfered Arc(PTA), oxygen-fuel thermal spray processes. In some cases, the coatedtubular member may be heat treated after the nickel-alloy coating isapplied to the end of the tubular member. The nickel-based coating alsoincreases the corrosion resistance.

Also, it should be understood that a coupling member may be cast ontothe end portion of a tubular member as discussed above or a couplingmember may be cast anywhere along the length or major axis of a tubularmember, e.g., in the middle of the tubular member. Thus, the casting isnot limited to the ends of the tubular member.

For example, FIGS. 14-19 illustrate an embodiment of a tubular member 40wherein the end portions 42, 44 are closed by a rotary swedging process.Moreover, an intermediate portion 46 is formed with a non-circularshape, e.g., hexagon, by the rotary swedging process (see FIG. 17).Thus, the tubular member 40 includes a non-circular shape in multipleareas, not just the end portions. As illustrated, the non-circularshapes are formed in localized areas and include reduced cross-sectionalareas. This arrangement provides flexibility to add joints in areasother than the end portions. That is, a coupling member may be cast overthe non-circular intermediate portion 46 of the member. Also, thenon-circular shape provides a mechanical lock to increase tensile andcompressive strength of the joint, and the non-circular shape increasesthe torsional strength of the joint.

FIGS. 20-24 illustrate another embodiment of a tubular member 50 havingend portions 52, 54 and an intermediate portion 56 deformed by aswedging process. As illustrated, the end portions 52, 54 are closed bythe swedging process, and the intermediate portion 56 is deformed by theswedging process to include a non-circular shape, e.g., hexagonal (seeFIG. 22).

In another embodiment, the hybrid component may include a hollow tubularmember having two or more components formed by a conventional process,e.g., stamping, roll forming, etc. The two or more components may bejoined using conventional welding processes. The tubular member may alsoinclude an extended section, e.g., flange, on one or both ends of thetubular member to close the end(s) of the tubular member. The extendedsection may be welded to close the end(s) of the tubular member. Thesize of the extended section used to close the end(s) of the tubularmember may be larger than the closure area in one or both dimensions tocreate an undercut feature, increasing the “pull-off” strength of thehybrid cast component. Optionally, the joint area of the tubular membermay include depressions formed during the stamping/forming process toprovide an undercut feature to increase the tensile strength (“pull-off”force) of the hybrid component.

Also, the tubular member may include hollow tubular/hydroformed shapesas discussed above, or may include solid geometric shapes. For example,coupling members may be cast on the end portions and/or intermediateportions of a solid geometric shaped member. An example is an I-beamshape with cast nodes on the end(s) or along the major axis of theI-beam shape.

The hybrid component 10 of the present invention is not limited to asuspension arm, as shown in the above-mentioned embodiments of theinvention. For example, the hybrid component 10 of the present inventionmay also be used as an engine mount 30, as shown in FIG. 8. Further, thehybrid component may be used in chassis, body, and power trainautomotive components. Additionally, the hybrid component may be used asa twist axle assembly 1000, as shown in FIG. 64.

Also, FIGS. 25 and 26 illustrate embodiments of an automotive rearcradle 60, 62, respectively, incorporating hybrid components. Asillustrated, the rear cradles 60, 62 are each formed with tubularmembers 61 and coupling members 63 cast onto the tubular members 61. Therear cradles 60, 62 incorporate hybrid components to provide a structurethat results in reduced cost and weight, while maintaining highstrength. For example, a cradle having a shape similar to cradles 60, 62comprised of 100% steel has a mass of about 22 kg and a cost of about$80. A cradle having a shape similar to cradles 60, 62 comprised of 100%aluminum has a mass of about 15.2 kg and a cost of about $125. Thecradles 60, 62 are comprised of about 47% aluminum and 53% steel, andhave a mass of about 15.6 kg and a cost of about $100.

Additionally, FIGS. 27 and 28 illustrate embodiments of hybrid controlarms 64, 66, respectively. As illustrated, the control arm 64 includes atubular member similar to tubular member 50 discussed above (the tubularmember 50 may have a curved configuration as illustrated in FIG. 27),and coupling members 14 cast onto the tubular member 50 at end portionsand an intermediate portion thereof. As illustrated, the control arm 66includes a tubular member similar to tubular member 40 discussed above(the tubular member 40 may have a curved configuration as illustrated inFIG. 28), and coupling members 14 cast onto the tubular member 50 at anend portion and an intermediate portion thereof.

The control arm 64 incorporates hybrid components to provide a structurethat results in reduced cost and weight, while maintaining highstrength. For example, a control arm having a shape similar to controlarm 64 comprised of 100% iron has a mass of about 6.2 kg and a cost ofabout $11. A control arm having a shape similar to control arm 64comprised of 100% aluminum has a mass of about 2.4 kg and a cost ofabout $13.50. The control arm 64 is comprised of about 35% aluminum and65% steel, and has a mass of about 2.7 kg and a cost of about $11.80.

Similarly, the control arm 66 incorporates hybrid components to providea structure that results in reduced cost and weight, while maintaininghigh strength. For example, a control arm having a shape similar tocontrol arm 66 comprised of 100% steel has a mass of about 4.13 kg. Acontrol arm having a shape similar to control arm 66 comprised of 45%aluminum and 55% steel and formed by aluminum casting and steelattachments has a mass of about 2.4 kg and a cost of about $12.50. Thecontrol arm 66 is comprised of about 33% aluminum and 67% steel, and hasa mass of about 2.13 kg and a cost of about $11.50.

FIGS. 29-33 illustrate an instrument panel support system 70 thatincorporates hybrid components. Specifically, the instrument panelsupport system 70 includes a tubular cross-beam 72, a main steeringcolumn/instrument cluster bracket 74, and left-hand and right-handmounting brackets 76, 78. The mounting brackets 76, 78 are structured tomount the support system 70 within a vehicle, and the main steeringcolumn/instrument cluster bracket 74 is structured to mount a number ofvehicle components, e.g., steering column, instrument panel, consolemount, glove box mount, etc. The instrument panel support system 70 isstructured such that the brackets 74, 76, 78 are molded, e.g., fromaluminum alloy, directly onto the cross-beam 72.

As shown in FIG. 30, the cross-beam 72 is formed from a single diametertube, e.g., steel tube, and anti-rotation devices, e.g., protrusions 73,for “as cast” brackets are incorporated onto the cross-beam 72. Also,the cross-beam 72 may include cap devices to prevent cast material,e.g., aluminum alloy, from entering the cross-beam 72.

As shown in FIGS. 31-33, each bracket 74, 76, 78 forms a one-piecestructure with multiple component attachment elements. By combiningattachment elements into a single structure, the number of parts can bereduced. Each bracket 74, 76, 78 is molded from a lightweight material,e.g., aluminum alloy, directly onto the cross-beam 72. This arrangementallows each of the brackets 74, 76, 78 to have a lower mass than thecombination of steel component attachment brackets, e.g., due to thelighter mass properties of aluminum. The wall thickness of the brackets74, 76, 78 may be cast thicker than steel thereby providing a more rigidbracket. Also, with the brackets 74, 76, 78 being cast onto thecross-beam 72, welding operations can be reduced which reducesmanufacturing complexity. This will reduce part distortion.Additionally, all the brackets 74, 76, 78 can be molded onto thecross-beam 72 in a common operation allowing for consistent bracket tobracket dimensional integrity. The NVH qualities of the brackets 74, 76,78 are also improved.

The present invention is not limited to the above-mentioned embodimentsof the invention. For example, the main body 12 and the coupling member14 may be made of an extruded article, casting, iron materials or othermetallic materials, or synthetic resin. Further, the present inventionis not limited by the use of the hybrid component 10 with a vehicle.

The hybrid component 10 of the invention allows the manufacturer to useless expensive materials for the tubular member 12, such as steel, orthe like, while using a relatively more expensive material, such asaluminum, or the like, for the coupling member 14, thereby reducing thecost of the hybrid component 10 as compared to conventional componentsmade entirely of aluminum. However, the entire hybrid component 10 canbe made of aluminum, or the like, if desirable.

It will be appreciated that the embodiments of the invention are onlyillustrative in nature, and that the principles of the invention can bepracticed in many different ways. For example, the principles of theinvention can be practiced with any type of attachment configurationbeside a J-hook or Y-hook configuration shown in the illustrativeembodiments, such as an X-hook, T-hook, or the like, to positivelysecure the coupling member to the tubular member.

In addition to the methods disclosed above, other methods can be used,together with the methods mentioned above to avoid the presence of acrevice between the tubular member 12 and the coupling member 14. Forexample, the tube surface can be coated prior to or after the castingoperation in the “joint area” to avoid any crevices that would causegalvanic corrosion. Another example is to apply pressure to the outsidesurface of the tubular member when the casting die closes and during themetal casting process, effectively reducing the physical dimension ofthe tubular member within the elastic range. When the casting die opensthe compressive force on the tubular member is removed and the tubeexpands within the constraint of the casting, thus minimizing the “gap”between the tubular member and the casting, avoiding any crevice thatcould result in galvanic corrosion. A further example is tometallurgically bond the tubular member and cast metal to avoid anycrevices that would cause galvanic corrosion. The bonding agent may beapplied using thermal spray processing. Examples of metallurgicallycompatible materials which can be sprayed include zinc-based,copper-based, and nickel-based alloys.

The embodiments of the subject application illustrated herein employ theconcept of fabricating hybrid “Hydrocast” modules, comprising one ormore high strength tube(s) or hydroformed components with castconnection or attachment points, and can yield significant weight andcost benefits. Weight savings can be realized by utilizing the highstrength-to-weight ratio inherent of tubular construction and the lightweight, machinability, near net shape, and ductility of cast metalalloys. The use of high strength cast alloys and processes which do notrequire heat treatment or which require only age hardening provide costsaving potential through energy avoidance.

Typical cast aluminum materials for automotive structural applicationsinclude aluminum, silicon and magnesium elements (AlSiMg 356 alloy) andaluminum, silicon, copper and magnesium elements (AlSiCuMg 357 alloy).The desired mechanical properties are achieved by solution heattreatment and artificial aging referred to as T6 or T7 heat treatment.The solution heat treatment process includes heating the aluminum toapproximately 1,000° F. (538° C.) followed by a water quench and anartificial age at a temperature of 400° F. (220° C.). Aluminum castingsmanufactured specifically using the semi-solid casting process do notrequire a solution heat treatment cycle to achieve an acceptable yieldstrength, typically greater than 180 MPa. Semi-solid castings have yieldstrength greater than 180 MPa with only an artificial aging (T5) heattreatment cycle, which involves exposing the aluminum casting to atemperature of 400° F. (220° C.).

The preformed steel component of the hybrid material casting may be anultra high strength steel (UHSS), boron steel or stainless steel havinga minimum yield strength of 1,300 MPa. The yield strength associatedwith the steel component is achieved by heat treatment quench andtemper. Exposure of the steel component to elevated temperatures of1,000° F., typical to that of aluminum solution heat treatmenttemperatures, results in a significant reduction in yield strength,below the 1,306 MPa design guideline. TABLE-US-00001 Yield StrengthYield Strength Grade Description 400° F. 1,000° F. 15B21 Boron Steel 840MPa 1,340 MPa 4130 UHHS 1860 MPa 1,160 MPa 4340 UHHS 1670 MPa 1,050 MPa420 Stainless Steel 1300 MPa 1,000 MPa.

The ability to fabricate a cast aluminum/steel hybrid component having ayield strength of a cast aluminum greater than about 180 MPa and a steelyield strength greater than about 1,300 MPa can be accomplished if thecast aluminum/steel hybrid component is not exposed to the aluminumsolution heat treatment temperature (typically 1000° F.). The semi-solidaluminum casting process enables the ability to obtain a minimum yieldstrength of 180 MPa by subjecting the hybrid component to a T5artificial age heat treatment (typically 400° F.), thus avoidingdegradation of the steel material properties which results from“overtempering” during the aluminum solution heat treatment processing.

Traditional aluminum casting methods require a T6 solution heattreatment (1,000° F.), quench and artificial age (400° F.) to realize ayield strength greater than that of 180 MPa. Exposure of high strengthsteel to a temperature of 1,000° F. reduces the yield strength to alevel below 1,300 MPa. Therefore, it is not possible using conventionalcasting methods to fabricate an aluminum/steel hybrid structurecomprised of a cast aluminum alloy having a minimum yield strength of180 MPa and a steel component having a yield strength greater than 1,300MPa. It is possible to fabricate a cast aluminum/steel hybrid componentusing the semi-solid casting process by subjecting the steel to only aT5 artificial age heat treatment.

If a cast aluminum/steel hybrid component is manufactured usingtraditional casting processes and the steel is subjected to the solutionheat treatment temperature of 1,000° F., the section size of the steelcomponent should be increased proportionally to compensate for thereduction in yield strength imposed by the heat treatment process. Thisincrease in section size may result in additional cost and weight of thesteel component, which offsets the advantage of making a cast aluminumhybrid component.

If a cast aluminum/steel hybrid component is manufactured usingtraditional casting processes and the cast aluminum is subjected to onlyan artificial age heat treatment temperature of 400° F., the sectionsize of the aluminum component should be increased proportionally tocompensate for the yield strength obtained by the T5 heat treatmentprocess. This increase in section size results in additional cost andweight of the aluminum component, which offsets the advantage of makinga cast aluminum hybrid component.

FIGS. 34-44 illustrate additional embodiments of the invention that canemploy any suitable casting process as discussed herein. FIGS. 34-36illustrate a bumper assembly 100 for a vehicle 112 constructed accordingto an embodiment of the present invention. As illustrated herein, thebumper assembly 100 illustrates one example of a bumper assembly thatuses a combination of heavier materials, such as steel, along withlighter materials to decrease the overall weight of the bumper assembly.The bumper assembly 100 is structured to be mounted to a space frame 114of the vehicle 112 at either the front end or the rear end of thevehicle 112. The bumper assembly 100 may be utilized on any suitablevehicle. An example of a prior art vehicle space frame is disclosed inU.S. Pat. No. 6,092,865 to Jaekel et al., which is incorporated hereinby reference thereto.

The main components of the bumper assembly 100 are longitudinallyextending tubular members 116, 118, first and second mounting members120, 122 attached to the tubular members 116, 118, a middle member 124attached to and extending between the tubular members 116, 118, and animpact-absorption device 126 attached to the tubular members 116, 118.The tubular members 116, 118 and the middle member 124 may togetherconstitute a bumper member 128 constructed to protect the vehicle 112from impact.

In the illustrated embodiment, the first and second mounting members120, 122 are rigidly mounted to the tubular members 116, 118 inspaced-apart relation such that the tubular members 116, 118 extendbetween the first and second mounting members 120, 122. Further, thefirst and second mounting members 120, 122 are positioned between thetubular members 116, 118 and the space frame 114 of the vehicle 112. Theimpact absorption device 126 is rigidly mounted on the other side of thetubular members 116, 118 and extends along the length of the bumperassembly 100. The bumper assembly 100 is mounted to the space frame 114of the vehicle 112 by rigidly mounting each mounting member 120, 122 tothe space frame 114. In use, the impact absorption device 126 ispositioned to receive collision forces during a front end or rear endcollision. The impact absorption device 126 collapses during thecollision in order to dissipate energy and thus reduce the magnitude ofcollision forces being transmitted to the bumper member 128 (tubularmembers 116, 118 and middle member 124) and the space frame 114.Examples of prior art bumper assemblies are disclosed in U.S. Pat. No.6,663,150 to Evans and U.S. Pat. No. 6,672,635 to Weissenborn et al.,the entireties of both being incorporated herein by reference.

In the illustrated embodiment, the bumper assembly 100 is structuredsuch that the mounting members 120, 122 are constructed of aluminumrather than steel. By using lighter mounting members 120, 122, theweight of the bumper assembly 100 is significantly reduced with respectto conventional bumper assemblies. In embodiments, the bumper assembly'sweight is about 45% less than conventional bumper assemblies.Additionally, aluminum mounting members 120, 122 also reducemanufacturing costs.

Further to modify the bumper assembly 100 for different vehicles, themanufacturer can simply modify the mounting members 120, 122 tocorrespond to the specific bumper mounting arrangement of a vehicle.This allows the tubular members 116, 118, the middle member 124, and theimpact-absorption device 126 to remain as common parts. Thus, theinterchangeability of mounting members 120, 122 for different vehiclessimplifies the manufacturing process and reduces manufacturing costs.

As illustrated, the tubular members 116, 118 include two substantiallyparallel tubular members. Each of the tubular members 116, 118 has agenerally circular cross-sectional configuration. Also, each of thetubular members 116, 118 is formed from steel and may have a hollow orsolid construction. However, each of the tubular members 116, 118 mayhave any other suitable configuration. Also, any number of tubularmembers can be employed, as desired.

The tubular members 116, 118 are bent to provide each tubular member116, 118 with opposing end portions 130, 132 and a centrally disposedintermediate portion 134 extending between the end portions 130, 132.The tubular members 116, 118 are bent to impart a longitudinal curvatureto the bumper assembly 100. The tubular members 116, 118 may be bentinto the desired shape in any suitable manner, e.g., roll forming,hydroforming. Further details of the hydroforming process are providedin U.S. Pat. No. 6,092,865 to Jaekel, which is incorporated herein byreference thereto. Also, the tubular members 116, 118 may vary in lengthand longitudinal curvature to suit various vehicle widths and contours.

The mounting members 120, 122 are constructed of aluminum and each ofthe mounting members 120, 122 fully encapsulates an end of each of thetwo tubular members 116, 118. Specifically, the mounting member 120fully encapsulates the end portions 130 of the tubular members 116, 118,and the mounting member 122 fully encapsulates the opposing end portions132 of the tubular members 116, 118. In the illustrated embodiment, themounting members 120, 122 encapsulate the tubular members 116, 118 bybeing cast onto the tubular members 116, 118. That is, whenmanufacturing the bumper assembly 100, the steel tubular members 116,118 are first formed, and then the aluminum mounting member 120 is castonto the end portions 130 of the tubular members 116, 118 and thealuminum mounting member 122 is cast onto the opposing end portions 132of the tubular members 116, 118. However, the mounting members 120, 122may be attached to the tubular members 116, 118 in any other suitablemanner, e.g., welding.

As shown in FIG. 36, each mounting member 120, 122 is in the form of abracket that provides upper and lower mounting plates 136, 138configured to mount the tubular members 116, 118 to the vehicle spaceframe 114. In the illustrated embodiment, each of the mounting plates136, 138 includes one or more openings 140 for mounting each mountingmember 120, 122 to the space frame 114, e.g., by fasteners. However, themounting members 120, 122 may be secured to the space frame 114 in anyother suitable manner, e.g., welding. Moreover, the mounting members120, 122 may have any other suitable structure to facilitate connectionto the vehicle 112.

The middle member 124 may be constructed of any suitable material, e.g.,steel, plastic composite, etc., and extends substantially along theentire length of the tubular members 116, 118. The middle member 124 isbent to provide the middle member 124 with upper and lower mountingportions 142, 144. The middle member 124 is also bent to impart alongitudinal curvature to the middle member 124 that corresponds to thelongitudinal curvature of the tubular members 116, 118. The middlemember 124 is attached to the tubular members 116, 118 such that theupper mounting portion 142 engages the tubular member 116 and the lowermounting portion 144 engages the tubular member 118. The middle member124 may be secured to the tubular members 116, 118 by welding, or in anyother suitable manner. The middle member 124 adds rigidity andreinforces the tubular members 116, 118. Further, the middle member 124distributes load being transmitted to the tubular members 116, 118.

In the illustrated embodiment, the impact-absorption device 126 isconstructed from a non-metallic material, e.g., foam. Theimpact-absorption device 126 extends substantially along the entirelength of the bumper assembly 100 to cover the tubular members 116, 118,the middle member 124, and the mounting members 120, 122. Theimpact-absorption device 126 may be securely mounted to the tubularmembers 116, 118 and/or the middle member 124 in any suitable manner,e.g., by fasteners, welding, etc. The impact-absorption device 126 isalso formed with a longitudinal curvature that corresponds to thelongitudinal curvature of the tubular members 116, 118. In use, theimpact-absorption device 126 dissipates energy being transmitted to thetubular members 116, 118, the middle member 124, and the space frame 114during a vehicle collision.

FIGS. 37-39 illustrate another embodiment of a bumper assembly 200. Asillustrated, the bumper assembly 200 includes a longitudinally extendingsteel bumper member 228 constructed to protect the vehicle from impact,first and second aluminum mounting members 220, 222 attached to one sideof the steel bumper member 228, and an impact-absorption device 226attached to an opposite side of the steel bumper member 228.

In the illustrated embodiment, the first and second mounting members220, 222 are rigidly mounted to the bumper member 228 in spaced-apartrelation such that the bumper member 228 extends between the first andsecond mounting members 220, 222. Further, the first and second mountingmembers 220, 222 are positioned between the bumper member 228 and thevehicle space frame. The bumper assembly 200 is mounted to the spaceframe of the vehicle by rigidly mounting each mounting member 220, 222to the space frame. In use, the impact absorption device 226 ispositioned to receive collision forces during a front end or rear endcollision. The impact absorption device 226 collapses during thecollision in order to dissipate energy and thus reduce the magnitude ofcollision forces being transmitted to the bumper member 228 and thespace frame of the vehicle.

The bumper member 228 is preferably formed from an elongated piece ofsheet metal, e.g., high strength steel. The sheet metal is bent toprovide a one-piece bumper member 228 with opposing end portions 230,232 and a centrally disposed intermediate portion 234 extending betweenthe end portions 230, 232. The sheet metal is also bent to impart alongitudinal curvature to the bumper member 228. The sheet metal may bebent into the desired shape of the bumper member 228 in any suitablemanner, e.g., roll forming, stamping, hot stamping, hydroforming.Further details of the hydroforming process are provided in U.S. Pat.No. 6,092,865 to Jaekel, which is incorporated herein by referencethereto. Also, the bumper member 228 may vary in length and longitudinalcurvature to suit various vehicle widths and contours.

The end portions 230, 232 and intermediate portion 234 of the bumpermember 228 cooperate to define an upper wall 250, a lower wall 252, anda central wall 254 between the upper and lower walls 250, 252. As shownin FIG. 38, one or more openings 256 are provided in the central wall254 for mounting the bumper member 228 to the impact absorption device226 and the mounting members 220, 222. Additionally, brackets and/orstiffening members 258 are attached between the upper and lower walls250, 252, e.g., by welding, to add rigidity/reinforcement to the bumpermember 228. For example, FIG. 37 shows bracket/stiffening members 258 inthe intermediate portion 234 of the bumper member 228.

The first and second aluminum mounting members 220, 222 are formedseparately from the bumper beam 228 and rigidly attached thereto. In theillustrated embodiment, the mounting members 220, 222 are attached tothe intermediate portion 234 of the bumper beam 228 between the endportions 230, 232. Each mounting member 220, 222 is in the form of amounting bracket that provides mounting plates 260, 262 and connectingwalls 264, 266 between the mounting plates 260, 262. The mounting plate260 of each mounting member 220, 222 is configured to mount to thevehicle space frame, and the mounting plate 262 is configured to mountto the central wall 254 of the bumper member 228. In the illustratedembodiment, the mounting plates 260, 262 include one or more openings268 for mounting, e.g., by fasteners. However, the mounting plates 260,262 may be secured in position in any other suitable manner, e.g.,welding. Moreover the mounting members 220, 222 may have any othersuitable structure to facilitate connection to the vehicle and bumpermember 228.

The first and second aluminum mounting members 220, 222 may be formed inany suitable manner, e.g., extrusion. Also, the first and secondaluminum members 220, 222 may be formed with an aluminum portion and asteel portion. Moreover, the aluminum mounting members 220, 222 areconnected to the steel bumper member 228 to prevent corrosion. Forexample, the members 220, 222, 228 may be coated with an anti-corrosivematerial. Additionally, the mounting members 220, 222 may be otherstructural members such as crush cans configured to absorb a collisionforce and deform in predetermined manner. For example, the connectingwalls 264, 266 of each mounting member 220, 222 may be structured todeform in a predetermined manner. Additionally, the aluminum members maybe made of any appropriate material that is lighter than steel (or thestronger material used for providing the strength to the bumper) and beformed as any element of the bumper assembly that can be made of alighter material to decrease weight while maintaining other elements ofthe bumper assembly of a stronger material such as steel.

The impact-absorption device 226 is constructed from a non-metallicmaterial, e.g., foam. The impact-absorption device 226 extendssubstantially along the entire length of the bumper member 228. Theimpact-absorption device 226 may be securely mounted to the bumpermember 228 in any suitable manner, e.g., by fasteners or welding. Theimpact-absorption device 226 is also formed with a longitudinalcurvature that corresponds to the longitudinal curvature of the bumpermember 228. In use, the impact-absorption device 226 dissipates energybeing transmitted to the bumper member 228 and the space frame during avehicle collision.

FIGS. 40-42 illustrate another embodiment of a bumper assembly 300. Asillustrated, the bumper assembly 300 includes a longitudinally extendingsteel bumper member 328 constructed to protect the vehicle from impact,first and second aluminum mounting members 320, 322 attached to one sideof the steel bumper member 328, and an impact-absorption device 326attached to an opposite side of the steel bumper member 328.

The bumper assembly 300 is substantially similar to the bumper assembly200. In contrast, the mounting members 320, 322 have a differentconfiguration and are attached to end portions 330, 332 of the bumpermember 328.

The first and second aluminum mounting members 320, 322 are formedseparately from the bumper beam 328 and rigidly attached thereto. In theillustrated embodiment, the mounting members 320, 322 are attached tothe opposing end portions 330, 332 of the bumper beam 328. Specifically,as shown in FIG. 41, each mounting member 320, 322 is attached to thebumper member 328 such that a portion of the mounting member 320, 322 isattached to the respective end portion 330, 332 and a remaining portionof the mounting member 320, 322 extends past the respective end portion330, 332. Thus, the bumper beam 328 is cut short of the mounting areasuch that it is positioned inboard of the outer attachment points of themounting members 320, 322.

Each mounting member 320, 322 is in the form of a mounting bracket thatprovides a tubular portion 380 and upper and lower mounting plates 382,384 extending from the tubular portion 380. The upper and lower mountingplates 382, 384 of each mounting member 320, 322 is configured to mountto the vehicle space frame, and the tubular portion 380 is configured tomount to the bumper member 328. In the illustrated embodiment, the upperand lower mounting plates 382, 384 include one or more openings 386 formounting, e.g., by fasteners, to the space frame. However, the mountingplates 382, 384 may be secured to the space frame in any other suitablemanner, e.g., welding. The tubular portion 380 is received within thespace defined by the upper, lower, and central walls 350, 352, 354 ofthe bumper member 328. The tubular portion 380 may be secured to thewalls 350, 352, 354 by welding or in any other suitable manner.Moreover, the mounting members 320, 322 may have any other suitablestructure to facilitate connection to the vehicle and bumper member 328.

Similar to the mounting members 220, 222, the mounting members 320, 322may be formed in any suitable manner, e.g., extrusion. Also, themounting members 320, 322 may be formed with an aluminum portion and asteel portion. Moreover, the mounting members 320, 322 are connected tothe steel bumper member 328 to prevent corrosion. For example, themembers 320, 322, 328 may be coated with an anti-corrosive material.Additionally, the mounting members 320, 322 may be crush cans configuredto absorb a collision force and deform in predetermined manner. Forexample, the tubular portion 380 of each mounting member 320, 322 may bestructured to deform in a predetermined manner.

FIGS. 43 and 44 illustrate another embodiment of a bumper assembly 400.As illustrated, the bumper assembly 400 includes a longitudinallyextending steel bumper member 428 constructed to protect the vehiclefrom impact, first and second aluminum mounting members 420, 422attached to one side of the steel bumper member 428, and animpact-absorption device 426 attached to an opposite side of the steelbumper member 428. Additionally, brackets and/or stiffening members 458are attached to the bumper member 428, e.g., by welding, to addrigidity/reinforcement to the bumper member 428.

The bumper assembly 400 is substantially similar to the bumper assembly200. In contrast, the mounting members 420, 422 have a differentconfiguration and are attached to end portions 430, 432 of the bumpermember 428 with connecting members 490, 492 formed of another material,e.g., a heavier material such as steel. Thus, a mounting bracketassembly 472 formed of bracket 420 and member 490 and a mounting bracketassembly 474 formed of bracket 422 and member 492, as illustrated inFIG. 44, can be used to attach the bumper assembly 400 to the spaceframe.

The first and second aluminum mounting members 420, 422 are formedseparately from the bumper beam 428 and rigidly attached to opposing endportions 430, 432 of the bumper beam 428 by connecting members 490, 492.Each mounting member 420, 422 is in the form of a mounting bracket thatprovides upper and lower mounting plates 482, 484 and a connecting plate485 extending between the upper and lower mounting plates 482, 484. Theupper and lower mounting plates 482, 484 of each mounting member 420,422 are configured to mount to the vehicle space frame, and theconnecting plate 485 is configured to mount to a respective connectingmember 490, 492. In the illustrated embodiment, the upper and lowermounting plates 482, 484 include one or more openings 486 for mounting,e.g., by fasteners, to the space frame. However, the mounting plates482, 484 may be secured to the space frame in any other suitable manner,e.g., welding. The connecting plate 485 is attached to a connecting wall494 of a respective connecting member 490, 492, e.g., by welding. Theconnecting member 490, 492 also includes upper and lower walls 496, 498that are secured to the upper and lower walls 450, 452 of the bumpermember 428 by welding or in any other suitable manner. Moreover, themounting members 420, 422 and connecting members 490, 492 may have anyother suitable structure to facilitate connection to the vehicle andbumper member 428.

Similar to the mounting members 220, 222 320, 322, the mounting members420, 422 may be formed in any suitable manner, e.g., extrusion. Also,the mounting members 420, 422 may be formed with an aluminum portion anda steel portion. Moreover, the mounting members 420, 422 are connectedto the steel bumper member 428 to prevent corrosion. For example, themembers 420, 422, 428 may be coated with an anti-corrosive material.Additionally, the mounting members 420, 422 may be crush cans configuredto absorb a collision force and deform in predetermined manner.

The bumper assemblies illustrated herein illustrate a few examples of abumper assembly that uses a combination of heavier materials, such assteel, along with lighter materials to decrease the overall weight ofthe bumper assembly. In the illustrated embodiment, the lighter materialis aluminum and the heavier material is steel. It should be understoodthat other materials could be used as desired. Also, the lightermaterial is illustrated primarily in the form of attachments for theheavier material such as mounting brackets. However, the lightermaterial can be any element of the bumper assembly, for example, thelighter material can be used for things such as panels or crush cans.

FIGS. 45-49 illustrate another embodiment of the present invention. FIG.45 illustrates, schematically an assembly 500 for casting metal parts,such as a vehicle cradle 62 as seen in FIG. 26. The assembly 500includes a main or shot tip pressure source 502 illustrated in the formof a shot tip 504 and a hydraulic cylinder 506. The shot tip 504 isfluidly coupled to a reservoir or biscuit 508 and contains, along withthe reservoir 508 a quantity of molten metal 510. The reservoir 508forms a shot sleeve that is fluidly connected to two die assemblies 512and 514. Die assembly 512 is comprised of at least two die elements 516and 518, which form a first die cavity or casting area 520. Die assembly512 has a restricted in-gate area 522 that is fluidly coupled to theshot sleeve 508 such that molten metal 510 is capable of being forcedthrough in-gate 522 and into cavity 520. Similarly, die assembly 514 iscomprised of at least two die elements 524 and 526, which form a seconddie cavity or casting area 528. Die assembly 514 has a restrictedin-gate area 530 that is fluidly coupled to the shot sleeve 508 suchthat molten metal 510 is capable of being forced through in-gate 530 andinto cavity 528.

In the Figures, the die assemblies 512 and 514 have been illustrated asseparate assemblies. It is apparent to those skilled in the art that thedie assemblies 512 and 514 can be combined into a single die assembly.The intermediate section between the two die assemblies can be utilizedto provide support to the support member 61, as described below.

Each die assembly 512 and 514 has at least one auxiliary pressure source532 and 534, respectively, that is attached to a point in the respectivecavity 520, 528 that is remote or distal from the in-gates 522, 530.Preferably, auxiliary pressure sources 532 and 534 are spaced as far aspossible from the in-gates 522, 530 and most preferably on opposite endsof the cavities 520, 528. The auxiliary pressure sources 532 and 534perform two functions. First, each auxiliary pressure source 532, 534provides an indication that its respective cavity 520, 528 issufficiently filled with molten metal 510 and, second, to applyauxiliary pressure to each respective cavity 520, 528 as describedbelow. Auxiliary pressure source 532 is illustrated in the figures as anauxiliary hydraulic cylinder having a piston 535 that is connecteddirectly to the die cavity 520. Piston 535 operatively communicates withthe cavity 520 and moves in a reciprocating fashion to define anexpanded volume and a desired volume.

Movement of the piston 535, including movement caused by molten metal510 filling cavity 520, can be monitored in various ways. FIG. 45illustrates a limit switch 536 adjacent piston 535 to track its movementin and out of the die cavity 520. Auxiliary pressure source 534 is alsoillustrated in the figures as an auxiliary hydraulic cylinder having apiston 537 that is operatively connected directly to the die cavity 528.Movement of the piston 537, including movement caused by molten metal510 filling cavity 528, can be monitored in various ways, but isillustrated as a limit switch or position sensor 538 adjacent piston 537to track its movement in and out of the die cavity 528.

In the illustrated embodiment of FIG. 45, the composite or hybridcasting assembly is casting the ends of a vehicle cradle 62, which hasmultiple support members 61 extending between multiple castings 63, asseen in FIG. 26. In FIG. 45, only one support member 61 is illustratedbut it should be understood that the other support members can be madein a substantially identical manner or in different configurations, asdesired, such as seen in FIG. 26. Support member 61 can take variousconfigurations, but is typically a tubular member, such as a highstrength steel, hollow tube. Tubes such as tube 61 can be made byoperations such as hydroforming, preferably according to known methodsas described in U.S. Pat. Nos. 5,979,201; 6,014,879; 6,065,502;6,474,534; 6,609,301; and 6,662,611.

To form cradle 62, tube 61 is to have a casting on each of two ends 544and 546 of the tube 61. Die assembly 512 has been configured to providethe casting for end 544 and die assembly 514 has been configured toprovide the casting for end 546. Although FIG. 45 shows only tube 61extending into cavities 520 and 528, multiple tubes such as tube 61 mayextend into each of cavities 520 and 528 and become integral with thecastings produced by die assemblies 512 and 514, as seen in FIG. 26.

The ends 544 and 546 of tube 61 extend into each cavity 520 and 528,respectively, and each end 544, 546 is closed so that molten metal 510does not enter the hollow tube 61. FIGS. 54 to 60 illustrate variousexamples of hollow tubes with a closed end. The various examples providetwo functions: closing the end of the hollow tube and providing amechanical interlock between the casting to be formed and externalsurface of the hollow tube. The mechanical interlock prevents relativemovement, torsional and axial, between the hollow tube and the casting.The mechanical interlock is enhanced by providing a mechanical interlocksurface.

In FIG. 54, the tube end is crushed between two dies to present a flatend that is wider than the tube. A hole is provided through the flat endto present an interlock surface.

In FIG. 55, a separate stamped cap is positioned in the inside of thetube, closing the end. The cap is tack welded or crimped to the tube.The cap may have a flange having a non-circular configuration to providea mechanical interlock surface.

In FIG. 56, a separate stamped cap is positioned in the outside of thetube, closing the end. The cap is tack welded or crimped to the tube.The cap may have a flange having a non-circular configuration to providea mechanical interlock surface.

In FIG. 57, a separate stamped cap is positioned on the end of the tube,closing the end. The cap is welded to the tube. The cap may have aflange or tang having a non-circular configuration to provide amechanical interlock surface.

In FIG. 58, the tube end is subjected to rotary swaging to shape the endin a bayonet shape.

In FIG. 59, the material is spun around the ends of the tube, withindents provided on the tube.

In FIG. 60, an end cap is welded to the end of the tube and a knurl isapplied to the outside surface of the tube to present a mechanicalinterlock surface.

FIG. 61 shows a flat end cap 600 abutting with an end portion of a steelmember 602. In accordance with the embodiment shown in FIG. 61, thesteel member is a tubular member. The end cap is fastened to the endportion of the steel member 602 by means of welding as indicated bywelding seam 604. Alternative methods of fastening the end cap can beemployed, such as crimping. Once the end cap 600 is fastened to thesteel member 602, a cast coupling member 606 is cast about the endportion of the steel member enclosing the end cap 600. The end cap 600prevents the molten metal from flowing into the steel member 602 andsimultaneously positively and rigidly locks and secures the castcoupling member to the steel member, as shown in FIG. 62.

FIGS. 63 a-e show exemplary embodiments of end cap designs. As can beseen from these figures, the end cap has a flange having a circular(FIGS. 63 a-b) or a non-circular configuration (FIGS. 63 c-e). Inaccordance with the embodiment shown in FIG. 63 b, notches are providedalong the flange to provide an additional mechanical interlock surface.FIGS. 63 c-e show examples of polygonal end cap configurations. Forexample, FIG. 63 c shows a hexagonal end cap configuration and FIG. 63 dshows an octagonal end cap configuration. In accordance with theembodiment presented in FIG. 63 e, the end cap has a flange having apolygonal shape including an outwardly extending member 660. Theoutwardly extending member 660 can generate additional torque which isadvantageous for high torque applications, such as for example in twistaxle assembly applications.

Each of the die assemblies 512 and 514 has a tube-receiving opening 545and 547 and the split or parting line between die elements 516, 518 and524, 526, respectively. Tube-receiving openings 545 and 547 areconfigured to complementarily receive tube ends 544, 546 respectively ina friction or interference fit. The tube-receiving openings 545 and 547will clamp and retain the tube 61 in place after the die elements 516,518 and 524, 526, respectively, have been closed. Although tube 61 hasbeen illustrated as being straight and symmetrical, hydroforming enablestube of complex geometries be utilized in the present invention. Toenhance the clamping capabilities, an intermediate die between the dieassemblies 512, 514, can be provided to receive the tube 61 and providesupport thereto, retaining the tube 61 in position during the castingprocess.

Preferably, the assembly 500, as illustrated in FIG. 45, is controlledby controller 550, which may take the form of a computer-basedcontroller assembly or other automated or manually monitored controllerassembly. Controller 550 can monitor and control the main pressure 502,the auxiliary pressures 532 and 534, and filling of the cavities 520 and528. In the illustrated embodiment, the filling of the cavities can bemonitored by controller 550 monitoring the sensors or limit switches 536and 538.

The operation of the embodiment illustrated in FIG. 45 is bestillustrated by viewing FIG. 45 in combination with FIGS. 46-49. The tube61 is positioned in the casting assembly 500 such that first end 544 oftube 61 is positioned within first mold 512 and a second end 546 of thetube 61 is positioned within second mold 514.

The first and second molds 512 and 514 are fluidly coupled to reservoir508 of molten metal 510. A main pressure is applied by hydrauliccylinder 506 and the molten metal 510 in reservoir 508 is forced intothe first mold cavity 520 through in-gate 522 and simultaneously intothe second mold cavity 528 through in-gate 530. The amount of pressureneeded from cylinder 506 to fill the cavities 520 and 528 is preferablymerely the pressure to overcome the resistance of pushing the moltenmetal 510 through the restricted in-gates 522 and 530. Thus, mainpressure is applied by cylinder 506 to the molten metal 510 in thereservoir 508 at an initial, mold-filling pressure to force or injectthe molten metal 510 into the mold cavities 520 and 528. As seen in FIG.46, as the molten metal 510 begins filling the cavities 520 and 528, themolten metal 510 encapsulates the ends 544 and 546 of tube 61.

The molten metal 510 is preferably aluminium. At the moment ofinjection, the molten metal 510 preferably contains about 40-50% solidsat less than 600° C., most preferably 583-595° C.

As seen in FIG. 47, the cylinder 506 continues applying the initialfilling pressure and the molten metal 510 completely fills each of themold cavities 520 and 528. The pistons 535, 537 for the auxiliarycylinders 532, 534 are free to move with the molten metal 510. Themolten metal 510 contacts the pistons 535, 537, and urges the pistons535, 537 outwardly, increasing the volume of the cavities 520, 528 suchthat the volume of each cavity is increased to an expanded volume.Pistons 535, 537 are pushed and displaced by the molten metal 510.

The displacement of the piston 535 and 537 may be measured or observedin any variety of ways well known in the art, such as by position sensoror limit switches 536, 538, respectively. Limit switches 536 and 538each generate a respective fill signal once the piston 535, 537 hastraveled a predetermined amount. The fill signal is transmitted to thecontroller 550 which responsively activates the auxiliary power sources532 and 534.

Other devices or mechanisms can be used to determine when the cavities520 and 528 are filled. Those devices may be integral or separate fromthe auxiliary pressure sources 532 and 534 or interactively connectedsuch as illustrated. For example, after experimentation with the processto determine how much time it takes to fill each cavity 520 and 528, thetiming routine may be established wherein pressures of the main 506 andauxiliary cylinders 532 and 534 are turned on and off based on apredetermined timing sequence. Also, a computer controlled system usingcontroller 550 may be used to automatically monitor the position sensorsor limit switches 536, 538 or other monitoring devices or methodologiesto determine when the cavities 520 and 528 are filled and when toactivate the auxiliary cylinders 532 and 534 and to control the maincylinder 506. Auxiliary cylinders 532 and 534 provide merely onemechanism for determining the fill of the cavities 520 and 528 and othermechanisms can be used that are part of or separate from the auxiliarypressure devices.

As seen in FIG. 48, with the main cylinder 506 still applying aninitial, fill pressure, or with the main cylinder 506 being turned offor relaxed; the auxiliary cylinders 532 and 534 apply auxiliary pressureto the molten metal 510 in mold cavities 520 and 528, respectively. Thisapplication of auxiliary pressure by cylinders 532 and 534 moves thepistons 535, 537 from the expanded volume to a desired volume andthereby injects a small amount of molten metal 510 back into the moldcavities 520 and 528 to compensate for or densify the solidifying metal,which shrinks upon cooling. The cylinders 532, 534 maintain apredetermined pressure on the molten metal 510 in each of the moldcavities 520 and 528 instead of relying solely on the main cylinder 506.Without the use of auxiliary cylinders 532, 534, the main cylinder 596would necessarily have to be operated to provide a relatively highpressure once the cavities 520 and 528 were filled with molten metal 510to provide sufficient pressure on the molten metal 510 in reservoir 508to continue injection of molten metal 510 into the cavities 520 and 528during the solidifying stage to ensure that the solidified metal castingconforms to the mold cavity. However, the use of the auxiliary cylinders532 and 534 permits the main cylinder 506 to apply a relatively lowerpressure than in previous casting systems and, as a result, the maincylinder 506 of the subject casting assembly 500 is permitted to besmaller than a main cylinder used in a system without auxiliary pressuresupplies 532, 534.

Depending on the casting process being carried out, the main cylinder506 may continue providing a low pressure to the molten metal 510 duringsolidification while the necessary pressure on the molten metal 510 forsolidifying in cavities 520 and 528 is applied by auxiliary cylinders532 and 534. Alternatively, the main cylinder 506 may be turned off orrelaxed once the auxiliary cylinder 532 and 534 begin applying pressureor at sometime thereafter.

Eventually, as seen in FIG. 49, the molten metal 510 begins solidifying.The molten metal 510 may initially begin solidifying at places such asat the in-gates 522 and 530 and in the shot sleeve 508. Once thein-gates 522 and 530 solidify, any pressure applied by the main cylinder506 will cease to be effective in applying the appropriate pressure toany metal still semi-molten in the cavities 520 and 528. FIG. 49illustrates a benefit of the auxiliary cylinders 532 and 534 in thateach cylinder continues applying pressure to the molten metal incavities 520 and 528, respectively, even after the in-gates 522 and 530are blocked by solidified metal 552.

Once the molten metal 510 is completely and sufficiently solidified, theauxiliary cylinders 532 and 534 are turned off and the die elements 516and 518 and die elements 524 and 526 are opened, respectively, to revealcasts 63 that are formed from the solidified molten metal 510 in moldcavities 520 and 528. As seen in FIG. 26, the casts 63 are rigidlyconnected to the tubular members 61 to form, for example, a vehiclecradle 62, such as a cradle front engine cradle or a rear cradle for anautomobile, as illustrated.

As seen in FIG. 50, one aspect of forming a metal casting is illustratedin the method of forming metal castings, comprising a position step 700of positioning a first end 544 of a structural member 61 in a first moldcavity 520; a second positioning step 702 of positioning a second end546 of the structural member 61 in a second mold cavity 528, the firstand second mold cavities 520 and 528 being fluidly coupled to areservoir 508 of molten metal 510; an applying step 704 of applying amain pressure to the molten metal 510 in the reservoir 508 to force themolten metal 510 into the first mold cavity 520 and the second moldcavity 528; and an applying step 706 of applying a first auxiliarypressure to the molten metal in the first mold cavity 520 and a secondauxiliary pressure to the molten metal in the second mold cavity 528such that the metal pressure in the first mold cavity 520 issubstantially equal to the metal pressure in the second mold cavity 528.

As seen in FIG. 51, another aspect of forming a composite metal castingis illustrated in the method of forming metal castings, comprising: apositioning step 710 positioning a first end 544 of a structural member61 in a first mold cavity 520, the first mold cavity 520 being fluidlycoupled to a reservoir 508 of molten metal 510; an applying step 712applying a main pressure to the molten metal 510 in the reservoir 508 atan initial, mold-filling pressure to force the molten metal 510 into thefirst mold cavity 520; another application step 714 of applying a firstauxiliary pressure to the molten metal in the first mold cavity 520; anda maintaining step 716 of maintaining the main pressure at or less thanthe initial, mold-filling pressure after the first mold cavity 520 hasbeen filled.

As seen in FIG. 52, another aspect of forming a metal casting isillustrated in the method of forming composite metal castings,comprising: the positioning step 718 of positioning a first end 544 of astructural member 61 in a first mold cavity 520, the first mold cavity520 being fluidly coupled to a reservoir 508 of molten metal 510; anapplication step 720 of applying a main pressure to the molten metal 510in the reservoir 508 to force the molten metal 510 into the first moldcavity 520; a detecting step 722 of detecting whether the first moldcavity 520 is sufficiently filled with molten metal 510 by monitoring amoveable element 535; and an application step 724 of applying a firstauxiliary pressure to the molten metal in the first mold cavity afterdetecting that the first mold cavity 520 is sufficiently filled.

The size of a semi-solid sub-liquidus casting (SLC) machine is definedby the platen size and the clamp tonnage. The platen size determines thelargest die dimension that can physically fit under the clamp of thepress. The clamp tonnage is defined by the product of the “projectedarea” times the metal pressure. Metal pressure relative to the size ofcasting defects and associated material properties is significant up toa metal pressure of 4 tons per square inch. Further increases in metalpressure in excess of 4 tons per square inch are reported to providelittle additional value.

In one embodiment of the system of FIGS. 45-49, the sub-liquidus casting(SLC) process semi-solid casting process includes the biscuit or moltenmetal reservoir 508 (typically 20″ diameter) from which molten metal 510is transferred into the die cavities 520 and 528 via a hydrauliccylinder 506 and shot tip assembly 504. The machine tonnage required isdetermined by the product of the metal pressure (i.e., approximately 4tons per square inch) times the sum of the projected area of the shottip (biscuit) assembly 504 and 508 and the projected area of thecastings outside the perimeter of the shot tip biscuit assembly 504,508.

The SLC process would ordinarily assume that the majority of the castingprojected area is located directly above the shot tip/biscuit area. Theplaten size is thus designed to accommodate a relatively large die,presenting metal pressure and casting projected area (shot tip pluscasting area) as the limiting features which define the machine tonnagerequirements.

The “controlled pressure” method of the subject application isparticularly applicable to the manufacture of “hybrid material” castautomotive components such as cradles which are typically separated byhigh strength steel tubes. Separation of the castings results in asignificant amount of the casting area to be outside of the projectedarea of the biscuit 508, thus increasing the machine size tonnagerequirement of, for example, main cylinder 506. The controlled pressuremethod utilizes the shot tip assembly 504, 508 to inject metal into thedies 520 and 528 and auxiliary cylinders 532 and 534 provide pressureafter the die cavities 520 and 528 are full. This technique results inlimiting the metal pressure during the die fill and initialsolidification phase to that of the machine clamp tonnage divided by thetotal projected area associated with the biscuit 504, 508 and castingarea 520, 528. Once the cavities 520, 528 are full, the shot tippressure is reduced and auxiliary cylinders 532 and 534 integral to thedie cavities 520 and 528, respectively, are actuated, providing pressureto only the casting projected area.

Specifically, this can be seen when taking a specific rear cradleexample:

CONVENTIONAL SLC CASTING METHOD Shot tip/biscuit diameter: 20 in Shottip/biscuit projected area: 314 in² Casting projected area 192 in²(outside perimeter of shot tip) Total projected area (casting & shottip): 506 in² (192 + 314) Required machine tonnage @ 2,000 ton 8,000 psi(4 tons/in²) metal pressure

CONTROLLED PRESSURE SLC CASTING METHOD IN ACCORDANCE WITH EMBODIMENTS OFSUBJECT APPLICATION Shot tip/biscuit diameter: 20 in Shot tip/biscuitprojected area: 314 in² Casting projected area (outside perimeter ofshot tip) 192 in² Metal pressure permitted at end of die fill 2 ton/in²Required machine tonnage @ 8,000 psi (4 tons/in²) 768 ton metal pressure

Thus, when using the method in accordance with the embodiments of thesubject application, the required machine tonnage is less than therequired machine tonnage using conventional methods and apparatus. Theembodiments of the subject application, which are referred to as“controlled pressure” casting, provides the capability to castcomponents such as a rear cradle or front engine cradle in one castingmachine cycle, in a reduced machine tonnage that is relative to only the“saleable” casting projected area (the casts 63 themselves) rather thesum of the projected area of the castings 63 and biscuit 508.

FIG. 53 illustrates a casting assembly 800 in accordance with anotherembodiment of the invention wherein one shot tip pressure assembly 802supplies molten metal to four casting die assemblies 804, 806, 808, 810so that two vehicle cradles 812 and 814 may be cast simultaneously. Eachvehicle cradle 812 and 814 is shown with two structural members 816 and818, respectively, and each engine cradle 812 and 814 can be similar tocradle 62 in FIG. 26. The structural members 816 and 818 may besubstantially identical to tube 61 in composition and make-up. Ofcourse, the specific shape of any structural members 816 and 818 willvary dependent upon the specific vehicle cradle formed. As mentionedabove, such an arrangement as illustrated in FIG. 53 is possible due tothe efficiencies of the casting assemblies disclosed herein in theembodiments of the subject application.

In FIG. 53, main pressure assembly 802 is fluidly coupled to the diecavity of each die assembly 804, 806, 808, 810 by shot sleeves 820, 822,824 and 826, respectively. Each die assembly 804, 806, 808, 810 receivesthe ends of two structural members 816, 818 so that the castings formedin each die assembly 804, 806, 808, 810 will encapsulate two ends of thestructural members 816 and 818. Each die assembly 804, 806, 808, 810also has an auxiliary pressure source 828, 830, 832, and 834, which issimilar to auxiliary pressure sources 532 and 534 described above. Also,the casting assembly 500 can be controlled by controller in a manner asdescribed above with respect to controller 550. Other than the mainpressure 802 supplying molten metal to four die assemblies 804, 806,808, 810, the configuration of the casting assembly 800 is substantiallyidentical to casting assembly 500 described above.

The embodiment of FIG. 53 illustrates one of the efficiencies of theillustrated embodiments of the subject application. That is, sinceauxiliary pressures are applied to each die 804, 806, 808, 810 duringsolidifying, the main pressure supplied to each die 804, 806, 808, 810by main cylinder 802 is less than the pressures typically applied bymain cylinders in prior art casting arrangements. Thus, since the mainpressure in the embodiments of the subject application are lower, thesize requirements of the pressure system and for the main hydrauliccylinder is less. This permits the embodiments of the subjectapplication to utilize smaller main hydraulic cylinders and smallerpressure requirements. Alternatively, with the same size and pressureconstraints found in the prior art, embodiments of the subjectapplication can be used to fill a greater number of die cavities withmolten metal. For example, wherein the a prior art configuration mayonly be used to cast one vehicle cradle member, embodiments of thesubject application may be used to produce more castings, for example,two cradle assemblies that each require two castings. Thus, whereas theprior art could make, for example, two castings per cycle, theembodiment of FIG. 53 may produce, for example, four casting per cycleusing the same pressure and sized machinery.

Thus, embodiments of the subject application utilize a minimum level ofhydraulic pressure required to transfer molten metal 510 from the shotsleeve 508 through the in-gates 522 and 530 to the die cavities 520 and528. The hydraulic pressure from the main pressure cylinder 506 that isneeded to fill the cavities 520 and 528 is much less than the hydraulicpressure needed from a main pressure cylinder of, for example, a priorart device that only relies upon one pressure source—the main pressuresource—to provide pressure during solidifying to reduce the volume ofentrapped air and increase the rate of heat transfer during solidifying.The embodiments of the subject application also incorporate moveablecores (squeeze pins) in the form of auxiliary hydraulic cylinders 532and 534 in each die cavity 529 and 528, respectively. The auxiliarycylinders 532 and 534 are capable of detecting that their respective diecavity 520 and 528 is full, prior to increasing the metal pressurewithin the cavities 520 and 528.

Embodiments of the subject application also simultaneously actuate theauxiliary hydraulic cylinders 532 and 534 acting as moveable cores toincrease metal pressure integral to each die cavity 520 and 528,respectively, which share a common submerged member 61. Thus,embodiments of the subject application illustrate a method of densifyingthe metal in multiple cavity dies 520, 528 to minimize the main pressureforce.

Also, embodiments of the subject application provide a method ofdetecting whether die cavities such as cavities 520 and 528 are filledwith molten metal 510 by using a moveable core, such as in the form ofauxiliary hydraulic cylinders 532 and 534.

FIG. 64 shows a hybrid torsion beam axle assembly according to anembodiment of the instant invention. The hybrid torsion beam axleassembly 1000 comprises a tubular member 1002 made of a metal material,such as for instance steel. The tubular member 1002 may be heat-treated.The tubular member 1002 can be formed to any desired shape by using anyconventional process. For example, the tubular member 1002 can be formedusing a hydroforming process, or the like, thereby forming a hydrocasthybrid component. In the instant embodiment, the tubular member 1002 isa steel torsion beam of the hybrid torsion beam axle assembly 1000.

The hybrid torsion beam axle assembly 1000 also includes a pair ofattachment or coupling members, such as for instance trailing arms 1004and 1006, connected one each to longitudinal opposite end portions 1008and 1010 of the tubular member 1002. The trailing arms 1004 and 1006 aremade by aluminum die casting, as described in greater detail below. Asused herein, the term “aluminum” denotes aluminum and its alloys.Optionally, the trailing arms 1004 and 1006 are made by magnesium diecasting, wherein the term “magnesium” denotes magnesium and its alloys.

Referring now to FIGS. 65-67, one aspect of the invention is the methodby which the trailing arms 1004 and 1006 are secured to the tubularmember 1002. In particular, as shown in FIG. 65, an end cap 1012 issecured to one end 1010 of the tubular member 1002. The end cap 1012closes the one end 1010 of the tubular member 1002. In the instantexample, the end cap 1012 comprises a flange 1014 (shown in FIG. 67)extending past the sidewall of the tubular member 1002, so as to providean anchor structure for retaining the cast trailing arm 1006. The flange1014 has a non-circular (polygonal) configuration to provide amechanical interlock surface, in particular an octagonal configuration.Optionally, the flange 1014 has an outwardly extending member asdiscussed above with reference to FIG. 20 e. The outwardly extendingmember can generate additional torque, which is advantageous for hightorque applications such as in the hybrid torsion beam axle assembly.Optionally, the flange 1014 has a circular configuration, either with orwithout an outwardly extending member. Optionally, the flange 1014 hasanother suitable configuration, such as for instance an ellipticalshape, a star-like shape or an irregular shape, etc.

Referring again to FIG. 65, the trailing arm 1006 is fabricated using acast-in-place technique, rather than using a conventional weldingtechnique. The cast technology used to form the trailing arm 1006 canbe, for example, high pressure aluminum die casting, low pressurepermanent mold, lost foam casting, squeeze cast, vacuum die cast,semi-solid casting, or the like. End cap 1012 is fastened to the end1010 of the tubular member 1002, such as for instance by welding. Theend cap 1012 seals the end 1010 of the tubular member 1002 to preventthe ingress or influx of the molten casting material into the tubularmember 1002 during the cast-in-place technique. The trailing arm 1006 isthen cast in place encapsulating the end cap 1012 and a portion of thetubular member 1002. In this manner, the trailing arm 1006 is positivelysecured to the tubular member 1002.

Referring now to FIG. 66, shown is partial cut-away view of the hybridtorsion beam axle assembly 1000. FIG. 66 shows the trailing arm 1006cast about the end of the tubular member 1002 and end cap 1012.

Of course, the trailing arm 1004 is fabricated similarly using acast-in-place technique. In particular, a not illustrated end cap sealsthe end 1008 of the tubular member 1002 to prevent the ingress or influxof the molten casting material into the tubular member 1002 during thecast-in-place technique. In this manner, the trailing arm 1004 ispositively secured to the tubular member 1002.

While the invention has been specifically described in connection withcertain specific embodiments thereof, it is to be understood that thisis by way of illustration and not of limitation, and the scope of theappended claims should be construed as broadly as the prior art willpermit.

What is claimed is:
 1. A hybrid torsion beam axle assembly, comprising:a steel torsion beam; an end cap fixedly secured to an end portion ofthe steel torsion beam; and a cast trailing arm cast about the endportion of the steel torsion beam including the end cap, therebypositively and rigidly securing the cast trailing arm to the steeltorsion beam.
 2. The hybrid torsion beam axle assembly according toclaim 1, wherein the steel torsion beam is tubular in shape.
 3. Thehybrid torsion beam axle assembly according to claim 1, wherein the endcap has a flange having one of a circular and a non-circularconfiguration.
 4. The hybrid torsion beam axle assembly according toclaim 3, wherein the flange has notches for providing a mechanicalinterlock surface.
 5. The hybrid torsion beam axle assembly according toclaim 1, wherein the end cap has a flange having a polygonal shape forproviding a mechanical interlock surface.
 6. The hybrid torsion beamaxle assembly according to claim 1, wherein the end cap has a flangehaving a polygonal shape including an outwardly extending member.
 7. Thehybrid torsion beam axle assembly according to claim 1, comprising aknurl on an outside surface about the end portion of the steel torsionbeam for providing a mechanical interlock surface.
 8. The hybrid torsionbeam axle assembly according to claim 1, wherein the steel torsion beamis made from one of high strength steel, ultra high strength steel,boron steel and stainless steel.
 9. The hybrid torsion beam axleassembly according to claim 1, wherein the trailing arm is cast fromaluminium or an alloy thereof.
 10. The hybrid torsion beam axle assemblyaccording to claim 1, wherein the trailing arm is cast from magnesium oran alloy thereof.